Motor controller switch



April l1, 1950 L. O. FRENCH MOTOR CONTROLLER SWITCH Filed March 28, 1947 INVENToR. (144 5 .TMQL

Patented Apr. 11, 1950 UNITED STATES PATENT OFFICE MOTOR CONTROLLER SWITCH Louis O. French, Milwaukee, Wis.

Application March 2,8, 1947, Serial No. 737,908

4 Claims.

The invention relates to speed regulators for electric motors and more particularly to regulators or controllers of the fluid pressure operated type.

When an electrical circuit is broken substantially simultaneously in a plurality of places, the voltage across either break will be less than Where only one break is used to stop the iiow of current, and as a consequence switch contacts used in making and breaking the circuit Will last longer in a multiple break switch than in a single break switch. The object of the present invention is to provide a motor speed controller switch mechanism having a multiple break to reduce contact wear and in which one of the switch elements preferably the bridging contact member is operable by the cooling air generated by the motors fan and cooperates with a pair of vibratory contacts connected to a control circuit of the motor to maintain the speed of the motor substantially constant, means also being provided for varying the effective action of the cooling air on said bridging contact to vary the speed of the motor.

. A further object of the invention is to provide a fluid pressure operated motor speed controller mechanism comprising a pair of freely vibratory contact members associated with a third freely vibratory air sensitive contact member whose frequency of vibration diiers from said pair of contact members so that good governing action is obtained.

A further object of the invention is to provide a iiuid pressure operated motor speed controller mechanism comprising a pair of freely vibratory contact members having the same or different frequencies of vibration associated with a third freely vibratory air sensitive contact member whose frequency of vibration differs from the frequency of either of said first named contact members so that good governing action is obtained.

A further object of the invention is to provide a fluid pressure operated motor speed controller mechanism comprising a pair of vibratory contacts associated with a third vibratory contact member in which the air sensitive target forv this last named contact forms the bridge for its switch contacts to simplify assembly and aid in the cooling of said contacts.

(Cl. ZOO-81.9)

A further object of the invention is to provide an air sensitive target forming a contact carrying bridge which is apertured adjacent said contacts to aid in cooling the same and in dissipating arcs that mayform at the contacts.

The invention further consists in the several features hereinafter set forth and more par-l ticularly defined by claims at the conclusion hereof.

In the drawings:

Fig. 1 is a plan view of speed controller embodying the invention;

Fig. 2 is a vertical sectional view taken on the line 2--2 of Fig. 1;

Fig. 3 is a detailed vertical sectional view taken on the line 3-3 of Fig. 1;

Fig. 4 is a detailed vertical sectional view taken on the line 4 4 of Fig. 1;

Fig. 5 is a Wiring diagram;

Fig. 6 is an outline view of the controller as associated with the motor to be controlled.

Referring to the drawings, the numeral 8 designates a support or housing of insulating material having a cylindrical opening 9 from which extends a slot I 0, said support adapted to be pivotally mounted on a plate I I by a pivot bolt I 2 and which plate may be provided with a suitable speed indicator scale, not shown herein, but shown in my copending application Serial No. '722.604, filed January 17, 1947, now Patent No. 2,480,566, granted August 30, 1949, cooperating with a pointer I3 on said support.

The support 8 is recessed at its back end I4 to receive a contact mounting block I5 which with a cover I 6 are secured to said support by screws I'I, the block and cover being of suitable insulating material.

The block I5 has a depending centrally disposed bcss to which the rear end of a resilient or vibratory contact carrying member I9 is an, chored by nails 20 or other suitable fastening means. The front end of the member I9 has an air sensitive target 2I secured thereto by rivets 22. While this target may be of insulating material, it preferably is formed as a metal disk forming a conductor bridge for a pair of spaced contacts 23 riveted or welded thereto. This disk also preferably has a series of small holes 24' drilled or otherwise suitably formed in it radially disposed relative to and close to eachl of said contacts 23 to permit cooling air streams to pass through said disk. On either side of the boss the rear ends of a pair of resilient or vibratory contact carrying members 24 are secured by terminal posts 25 in the form of bolts passing through apertures in said block l5 and carrying a clamping nut 26 and a conductor binding nut 21. Each member 24 has a contact 28 riveted thereto and to a metal plate or washer 29, and each contact is so disposed as to normally engage its cooperative contact 23 on the bridge member 2l, said members 24 and the member I9 being biased to a normally closed contact position and their tensions so adjusted that the bridging member will simultaneously or substantially simultaneously open the circuit between both sets of contacts under the action of..

air pressure upon the target 2 i Referring to Fig. 5, the numeral '30 vdesignates Y current supply wires, one of which is connected to the armature 3i of the motor whose speed is to be controlled and the other .of which is connected with the field 32 of said motor through a circuit closure C embodying this invention Whose contacts 28 through the bridging member 2| is in series with said eld. A condenser 33 and a high ohma'geresistor l'34! may be connected in parallel'acros's the terminals of the closure C to the motor housing 31 draws air through the inlet 38 in said housing and forces this air through the motor and through an outlet at the other `end of the motor to cool the same. The plate Il is mounted on a boss 39 formed on 'the motor housing at its inlet and has an opening 40 alined with said inlet 38 and the opening 9 in the support 8, which support being pivotally mounted on said plate may be swung so 'as "to partially or wholly displace the opening 9 relativeV to the openings 38 and 40. y

With the abovearrangement when current is supplied 'to the line 'wires 3U, the motor is started and the cooling`fanf35 set in motion to draw cool-7 ing air through the motor and past the openings 9, 40 and 38,some of this air acting on the target 2| .and overcoming the normal closing bias of the contact carrying members I9 and y24 and causing the contacts 23 and '28 to separate, thus opening the current supply circuit to the motor and reducing itsspeed until the reduced suction effect permits the Acontacts to again engage. This action is rapidly repeated `with the result that the speed 'of the motor `is maintained substantially constant for any given suction eiect on the target 21. If then the support is 'swung from its initial position in which the opening 9 alines with the opening 4] to a position in which the target only partially overlaps said opening, the suction effect will be reduced and the speed of the motor will be increased until iinally when the target '2l 'is moved completely y'out of the iniiuence of the suction effect of the fan 35, the contacts 23 and 28 will Vremain closed or substan tially closed'and the motor 'will run at its highest speed. The Contact carrying members 4Il! and 24 are all free to vibrate, and the member I9 due to the target v2l has a different frequency of vibration from that ofthe members 24. The members '24 may each vibrate at `the same yfrequency or may' have Ydifferent 'frequencies :of 'vibration which coincide at different intervals, and as a. result the motor circuit will be opened and closed both by the vibrating action of the member I9 and the members 24, so that for any given setting of the support 9 the speed of the motor will be maintained substantially constant, it being noted that the action of the fan produces a pulsating or vibratory effect on the air drawn into the motor, that the motor itself may set up vibrations in the contacts iid possibly arcing effects between the contacts and the vibrations of one set of contacts will act to vibrate the other contacts. As in the present construction any arcing between the contacts is distributed over a relatively large contact area, and as the circuit may be simultaneously broken at a plurality ci contacts instead of through one set of contacts, rapid deterioration ofthe contacts will be prevented. The holes 24 in target 2l in addition to permitting cooling streams of air to pass the contacts also permit said streams to dissipate arcs that may form at `said contacts.

While the circuit closure C has been shown l mounted at the inlet opening for the motor ventilating system, it may also. if desired, be mounted at the outlet opening in which instance the contact member I9 with its 'target would be mounted on a centrally recessed portion of the block l5 'instead of the boss I8 and be disposed outwardly of the discharge or outlet opening ofthe motor lhousing and the members 24 mounted on spaced bosses similar'to the Aboss 1I 9 herein shown sothe air pressure would tend to move the contacts k23 away from the contacts 28 in the .same way that the suction pressure accomplishes this in the form shown andthe shifting of the support 9 relative to said outlet `will act in the same way to vary the speed of the motor. Instead of making the target 2| as a part of the bridging contact it could be Aof insulating material and arranged to act on the members 24 to tend to separate them from the bridging Contact member `without departing from the present invention.

The construction above rdescribed provides a simple form of speed controller connected in a control circuit for the motor to effect its change in speed through awide speed range while maintaining ts speed substantially constant vat any selected speed within said range.

I desire it to be understood that this invention is not to be limited to any particular form or ar-y rangement of parts except in so far as `such limitations are included in the claims.

What I claim as my invention is:

1. In a circuit control switch for controlling the speed of a fan cooled 'electric motor, the combination of a pair of freely vibratorv resilient members having contacts at their outer 'free end portions, and a freely vibratory member having bridged contacts at its outer'free end portion and cooperating with said first named contacts and having an air sensitive target for eiecting its vibratory movement relative to said iirst named members under the air ow effect produced by the motor to maintain the speed of said motor substantially constant.

2. The control switch as dened in claim l in which the target carrying lvibratory member has a frequency of vibration different from said pair of vibratory members.

3. The control switch as dei'lned vin claim 1 in which the kpair of vibratory members have different frequencies of vibration.

4. vrIhe control switch ais defined .inrcl'aim v1 in' which the pair of freely vibratory contact 'car- 5 rying members have diierent frequencies of vibra- Number tion and the target carrying vibratory member 2,092,955 has a frequency differing from those of said rst 2,239,738 named members. 2,292,567 LOUIS O. FRENCH. 5 2,312,241 2,389,880 REFERENCES CITED 2,425,178 The following references are of record in the file of this patent:

lo Number UNITED STATES PATENTS 67,967 Number Name Date 1,494,189 Russell et al May 13, 1924 Name Date Chamberlain Sept. 14, 1934 Russell Apr. 2'?, 1937 Jordan Aug. 11, 1942 Brachenburg Feb. 23, 1943 Weber Nov. 27, 1945 Ellerbeck Aug. 5, 1947 FOREIGN PATENTS Country Date Austria Aug. 1, 1914 

